Ron Micjan has a good teardown articles on his
tmi Website of both KISSes as well as the TravelKiss prototype.
My
DEMA report for Rebreathers Worldwide gives you another look at it.
If you want something in print, the SportKiss is covered in the current issue of
Advanced Diver Magazine . You'll also find some additional UW images from Zero Gravity 4.0 on ADM's website.
There are also a couple of fairly small and light electronically controlled CCRs.
The (hopefully) soon to be released Evolution is about 2/3 of the hight of the Inspiration and according to APD weights 25 kg/52 lbs. (including the BCD & harness)
The MiniMeg is a small(er scrubber cannister) version of the Megalodon. ISC hasn't published the specs, but I've seen them several times and they are more compact as the aluminum cannister doesn't encase the tanks. This also allows you to choose tanks at your destiantion that wouldn't fit the Evo.
The Prism, while a bit larger than the Evo and MiniMeg, also allows tank choices (some of which won't let you fit the optional cowling) and is probably the lightest weight eCCR at 47 lbs. ready to dive. 6 lbs of that are absorbant (which get the rig its 5 hrs rating versus the MiniMeg/Evo's 2 hrs and the SportKiss' 2.5 hrs), and if you can leave the tanks at home it really travels well.
As you mention simplicity too, none of the eCCRs can beat the SportKiss in that respect, probably the reason 'simple' is part of its name.
That being said, the Prism is as simple as an eCCR can be, the Evo would probably be next, and finally the Meg.